1. Field of the Invention
The present invention relates to an endoscope apparatus which enhances observation performance by reliably removing an extraneous matter on an observation window surface.
2. Description of the Related Art
In recent years, with the purpose of performing minimally invasive medical care, surgery using endoscopes has become widespread. In such an endoscopic operation, a challenge is to prevent deterioration of an observation environment due to adherence of contaminations and occurrence of fogging to the observation window placed at an endoscope distal end portion.
In some endoscopes for digestive organs, fogging and contaminations are removed by supply of water to the lenses at the endoscope distal end portions, but in surgical endoscopes, the adhering contaminations are sometimes blood, fats and the like scattered by surgical operations, and the contaminations cannot be removed simply only by water supply in many cases. Further, among the endoscopes for digestive organs, in some transnasal type endoscopes, the distal end portions are thin, and the components are densely arranged. Therefore, removal of the droplets after water supply can be sometimes insufficient.
As countermeasures against the problem, the art disclosed in Japanese Patent Application Laid-Open Publication No. 2006-55275 is known, for example.
In this conventional endoscope apparatus, at a distal end of an inner tube of an insertion portion, a cover glass as an image capturing window is attached to correspond to an objective optical system. A coating layer that is a hydrophilic treatment layer having hydrophilicity of, for example, a photocatalyst (titanium oxide or the like) is formed on an outer surface of the cover glass.
When condensation occurs on the cover glass due to a temperature difference from the ambient environment, the coating layer diffuses the water particles by the hydrophilicity to form a water film in a thin film shape to prevent the surface from being fogged. More specifically, by formation of the water film, a clear field of view which is in the initial state is ensured without causing fogging on the cover glass outer surface. Contaminations such as a body fluid, and droplets by an electric knife not illustrated contact the water film formed on the coating layer of the cover glass, these contaminations adhere to the water film.
Further, the inner tube of the insertion portion is provided with an ultrasound transducer to be capable of transmitting vibration to the cover glass. The ultrasound transducer is subjected to drive control to oscillate to generate ultrasound vibrations, and the ultrasound vibrations are propagated to the cover glass. Here, in the conventional endoscope apparatus, by the action of the ultrasound vibration propagated to the cover glass and the gravity, the water film formed to adhere to the coating layer on the outer surface of the cover glass drops and is removed. At this time, the contamination adhering to the water film is also dropped with the water film, and cleaning of the outer surface of the cover glass is performed. The water film also can be formed by replenishing water onto the coating layer by a water supply nozzle or the like. By the above, the extraneous matters (contaminations, water droplets and a water film) on the outer surface of the cover glass are removed.